Well that means you do not have full permissions on your mailbox itself. For
this you will have to contact your Exchange Admin and ask him to assign you
full permissions on your mailbox. Also you can try out another option.
1. Go to Tools, Options and click on Delegate tab.
2. Here Click on Add which will pull up Global Address List. From here you
can add people whom you want to share your calendar with.
3. In the next screen make sure for Calendar the Edit permission is given,
you can also see two more options. Its up to you if you wish to select those.
4. Once done your boss can access your Calendar.
Your Boss will have to go to File->Open other users folder and then type in
your display name and select Calendar from the drop-down. This way he can
access your calendar.
Regards
Nitin Nair
MCSE